EP0245533B1

EP0245533B1 - Three dimensional woven fabric connector

Info

Publication number: EP0245533B1
Application number: EP86106650A
Authority: EP
Inventors: Dale Abildskov
Original assignee: Fiber Science Inc
Current assignee: Fiber Science Inc
Priority date: 1986-05-15
Filing date: 1986-05-15
Publication date: 1990-10-10
Also published as: EP0245533A1; DE3674922D1; ATE57398T1

Abstract

A three dimensional woven fabric connector includes a first generally planar section of flexible fabric (40) composed of fibers which run lengthwise and are interwoven with fibers that run crosswise generally at right angles to the lengthwise fibers, and a second generally planar section (44,48) of flexible fabric composed of lengthwise and crosswise fibers interwoven generally at right angles to one another. The second section (44,48) of fabric is interwoven with the first section (40) along an intersection (52,56) of the two sections, with at least one lengthwise fiber being common to the two sections. At least some of the crosswise fibers of each section extend from that section through the intersection to the other section.

Description

This invention relates to a fabric joint for providing three-dimensional structural support, to a three-dimensional woven connector formed by said joint and to the application of said joint for joining structural aircraft components.
A type of a fabric joint connector is known from applications in the aircraft industry to join structural components such as spars or ribs to wing skin coverings. Said L-shaped fabric joint connectors are bonded by adhesive to both structural components. Although creating a light-weighted joint, typical strength and efficient load transfer in only a limited number of directions is achieved, while presenting weaknesses in other directions, which, e.g. lead to peeling problems.
A joint known from US-A 4 395 450 contains a resin impregnated woven fabric connector with intersecting fabric panels which are interwoven with an intermediate laterally extending panel. The connector is used for joints of aircraft structural members. The fiber orientation is predominately transverse.
Woven fabric material for high load applications is known from US-A 3 991 249 and US-A 3 090 406 in which intersecting fabric sections use at least one common weft thread. The line of intersection between the sections of the fabric material extends perpendicular to the weaving or warp direction.
DE-C 357 353 and US-A 3 538 957 disclose three-dimensional fabric having lines of intersection between connected sections of the fabric, said lines of intersection extending in weaving or warp direction.
It is a task of the invention to create a fabric joint for providing three-dimensional structural support for at least two adjoining structural members which is useable as a connector providing strenght and efficient load transfer in a multiplicity of directions and which uniformly distributes loads and stresses between joined structural components.
This is achieved with a fabric joint according to claim 1, which can be used as a three-dimensional woven connector according to claim 12 for forming a joint according to claim 19.
With this configuration, strength and efficiency and uniform load transfer is provided in lengthwise and crosswise directions of the fiber bundles or fiber strands. Preferred embodiments are disclosed in the depending claims.
Embodiments of the invention are described in accordance with the drawings, in which:

FIG. 1 shows a fragmented, cross-sectional view of a prior art arrangement for connecting a structural support to a structural covering;
FIG. 2 is a fragmented, cross-sectional view of a three-dimensional woven connector, in the form of an H, made in accordance with the principles of the present invention;
FIG. 3 is a cross-sectional view of another embodiment of a three-dimensional woven connector, in the form of a T with two legs;
FIG. 4 is a cross-section of another embodiment of a three-dimensional woven connector in the form of a Y;
FIG. 5 is a perspective view of a schematic showing of the crosswise fibers interwoven with the lengthwise fibers of the connector embodiment of FIG. 2;
FIG. 6 is a perspective view of a schematic showing of the crosswise fibers interwoven with the lengthwise fibers of the connector embodiment of FIG. 3;
FIG. 7 is a perspective view of a schematic showing of the crosswise fibers interwoven with the lengthwise fibers of the connector embodiment of FIG. 4; and
FIG. 8 is a fragmented view showing the manner in which crosswise fibers may be interwoven with lengthwise fibers in the woven connector of the present invention.

Referring now to the drawings:

FIG. 1 shows a prior art arrangement for connecting a spar or rib 4 (such as might be used in construction of an airplane wing) to another structural component 8 (such as the skin or covering of an aircraft wing). Placed at the joint of the spar 4 and structural component 8 to hold the two together are a pair of fabric connectors 12 and 16 (shown in cross section in FIG. 1). A portion of each fabric connector 12 and 16 is placed flat against and bonded to the structural component 8 while another portion is placed flat against and bonded to the spar 4 as shown. This connector arrangement provides fairly good strength and load transfer efficiency between the spar 4 and structural component 8 when the two components are moved as indicated by arrows 20 relative to one another. However, the strength of the connector is very weak when the two components are moved in the direction indicated by arrows 24 and 28 relative to one another. In particular, such movement would give rise to well known fabric connector peel problems.
The three-dimensional woven fabric connector of the present invention avoids the problems outlined in connection with the FIG. 1 arrangement, and one embodiment of the connector is shown in fragmented, cross-sectional view in FIG. 2. This embodiment is shown connecting a spar 34 to a skin covering 38, such as used in the construction of aircraft. It is noted that both the spar 34 and skin covering 38 are shown as being made of a sandwich wall construction. It should be understood that the woven fabric connectors of the present invention may be used to connect together a variety of structural components in addition to those shown in the drawings.
The connector embodiment of FIG. 2 includes a first section of fabric 40 composed of fibers interwoven together in a cross-hatched pattern as will be described in detail later. Also included are second and third sections of fabric 44 and 48 also composed of fibers interwoven together in a cross-hatched fashion. The second and third sections of fabric 44 and 48 are also interwoven with the first section 40 along respective intersections 52 and 56 of the sections. The locus of points at which section 44 intersects section 40 and the locus of points at which section 48 intersects section 40 are spaced apart and generally parallel in the plane of section 40. As will be explained further later on, at least one fiber or fiber bundle of the section of fabric 40 is common with the section of fabric 44, and at least one other fiber or fiber bundle of section 40 is common with section 48.
As seen in FIG. 2, portions of both sections 44 and 48 extend upwardly from section 40 and portions also extend downwardly therefrom. Likewise, a portion of section 40 extends outwardly in one direction from section 44, and another portion of section 40 extends outwardly in the opposite direction from section 48, with an intermediate portion of section 40 extending between sections 44 and 48. The sections 44 and 48 are shown as intersecting section 40 at right angles, but other angles of intersection could also be used as needed. Additionally, the fabric sections are bendable and thus may be made to conform to variety of shapes to which they might be bonded.
The spar 34 and skin cover 38 are connected together by placing section 44 flat against the underside of the skin covering 38 and bonding it thereto. The two upper portions of sections 44 and 48 extend into the skin covering 38 and are bonded to the interior of the skin section covering. The edge of the spar 34 is placed between the two lowermost portions of sections 44 and 48 and is bonded therebetween. A spar section 60 is also positioned between the two upper portions of the sections 44 and 48 as shown in FIG. 2. With this configuration, structural strength and efficient load transfer is achieved in all three directions of movement which the spar 34 may have relative to the skin covering 38.
FIG. 3 is a cross-sectional view of another embodiment of the woven fabric connector of the present invention. This embodiment also is shown coupling together a spar 64 to a skin covering 68. The connector of FIG. 3 includes a first section of woven fabric 72, and second and third sections of woven fabric 76 and 80 which are interwoven with the section 72 to extend downwardly therefrom as shown. The sections of fabric 76 and 78 intersect the section of fabric 72 along generally parallel loci of points at which intersections a fiber or bundle of fibers is common with the section 72 and respective sections 76 and 80.
The connector of FIG. 3 is utilized by placing section 72 flat against the bottom surface of the skin covering 68 and bonding it thereto. The spar 64 is positioned between sections 76 and 80 and is bonded to the sections, and to the underside of section 72.
FIG. 4 shows a cross-sectional view of still another embodiment of the woven fabric connector of the present invention. Specifically, two connectors 84 and 88 are shown interconnecting, at a right angle, the edges of two skin covers 92 and 96. Each of the connectors, such as connector 84, includes three sections 100, 104 and 108, all of which extend generally radially outwardly from an intersection 112 of the three sections. The three sections are composed of fibers interwoven together, with at least one fiber or bundle of fibers being common to the three sections.
The connector 88 is similar to the connector 84 except two of the sections are bent to overlie the outside corner of the joint of the two skin coverings 92 and 96, as shown. Two of the sections of connectors 84 and 88 extend into the joint between the skin coverings 92 and 96 generally in planes parallel to one another. The different sections of the two connectors 84 and 88 are bonded to the surfaces of the skin coverings with which they are placed in contact.
FIG. 5 shows a schematic representation of the weaving of the connector embodiment of FIG. 2. The connector incudes lengthwise fibers or fiber bundles 120 which serve as the warp of the woven fabric. Interlaced through the lengthwise fibers 120 or warp are crosswise fibers or fiber bundles 124 which serve as the weft of the fabric. The crosswise fibers 124 of section 48 are interwoven about a lengthwise fiber or bundle of fibers 56 which is common and serves as an intersection with section 40. Similarly, the crosswise fibers 124 of the section 44 are interwoven with a lengthwise fiber or bundle of fibers 52 which is also common with the section 40. The common fiber or fiber bundle 52 is spaced from and generally parallel with the fiber or fiber bundle 56, as indicated in FIG. 5.
The crosswise fibers 124 are interwoven through the lengthwise fibers 120 to an edge of a section, such as section 48, and then extend about the edge and back through the lengthwise fibers 120 substantially without break. That is, the crosswise fibers 124 are looped about the edgemost lengthwise fibers without a break in the crosswise fibers. Although not indicated in the FIG. 5 embodiment, the crosswise fibers of one section may extend through the intersection with another section to form the crosswise fibers of that other section.
FIG. 6 shows schematically the interweaving of fibers of the woven fabric connector embodiment of FIG. 3. This connector also includes lengthwise fibers 130 interwoven with crosswise fibers 134, 138 and 142. The crosswise fibers 134 are shown interwoven with the lengthwise fibers 130 to form section 72 (as also shown in FIG. 3. Similarly, crosswise fibers 138 and 142 are interwoven with lengthwise fibers to form section 76 and 80 respectively. It is noted that the crosswise fibers in each of the sections do not extend into the other sections, other than extending to and about the fibers or fiber bundles 146 and 150 which are common to intersecting sections.
FIG. 7 is a schematic showing of the interweaving of the fibers for the woven fabric connector embodiment of FIG. 4. In this embodiment, crosswise fibers 160 are interwoven with lengthwise fibers 164 and extend from one section through the intersection 168 to form crosswise fibers of another section. In FIG. 7 the crosswise fibers extend from one section through the intersection 168 to a next section, and then from that section through the intersection 168 to the third section of fabric.
FIG. 8 shows a fragmented section of fabric which includes lengthwise fibers 180 interwoven with a continuous crosswise fiber 184. The crosswise fiber 184 is interwoven in one direction through the lengthwise fibers 180 and then about the edgemost lengthwise fiber and back in the other direction through the lengthwise fibers, etc. This continuous looping or weaving of the crosswise fiber forms advancing columns of weft in the fabric as generally indicated in FIG. 8.
The fabric connectors of the present invention are advantageously woven of fiber bundles of graphite, fiberglass, Kevlar, or similar high strength material.
Although different specific embodiments of the invention have been described, all such embodiments provide a three-dimensional woven fabric connector which provides a type of three-dimensional structural support. All of the embodiments include sections which are interwoven together and intersect at a common locus or loci of points. Each of these embodiments provides strength and efficient load transfer in three dimensions. The connectors, in addition to providing strong reliable connectors, are very lightweight.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention and the appended claims are intended to cover such modifications and arrangements.

Claims

1. A fabric joint for providing three dimensional structural support for at least two adjoining structural members (34, 38; 64, 68, 92, 96) comprising a first section (40, 72) of fabric for attachment to one of the structural members and composed of fiber bundles or fiber strands interwoven together as warp (130; 164; 180) and weft (121; 131; 160; 184), and

a second section (44, 76) of fabric for attachment to the other of the structural members and also composed of fiber bundles or fiber strands interwoven together as warp (120) and weft (124, 138), and interwoven with said first section (40, 72) along an intersection (52; 146; 168) of the two sections, with at least one fiber bundle or fiber strand of the warp, located at the intersection, being common to the two sections, and

wherein at least some of the fiber bundles or fiber strands of the weft (124, 131, 160) of the first section extend through the intersection to form at least some of the fiber bundles or fiber strands of the weft (124, 138) of the second section (44, 76).

2. A fabric joint as in claim 1 wherein the fiber bundles of the weft (124; 131, 138, 160) of each section (40, 44; 72, 76) are interwoven through the warp (120, 130, 164, 180) in one direction to an edge thereof and then about the edge and back through the warp (120, 130, 164, 180) in the opposite direction substantially without break in the fiber bundles.

3. A fabric joint as in claim 2 wherein the weft (124; 131; 138; 160) extends generally at right angles to the warp (120, 130, 164, 180).

4. A fabric joint as in claim 1 further comprising a third section (48, 80) of fabric for attachment to one of the structural members (34, 48; 64, 68) at a location spaced from that at which either the first or second section is attached and composed of fiber bundles or fiber strands interwoven with the first section (40, 72) along a second intersection (56, 150) of the first and third sections which is in general parallel with and spaced apart from the first mentioned intersection (52, 146), with at least one fiber bundle or fiber strand of the warp (120, 130) located at the second intersection (56, 150) being common to the first and third sections (40, 72; 48, 80).

5. A fabric joint as in claim 4 wherein the second and third sections (44, 76; 48, 80) each extend laterally in opposite directions from the first and second intersections (52, 56; 146, 150) respectively, and wherein the first section (40, 72) extends outwardly from the second section (44, 76) in one direction and outwardly from the third section (48, 80) in the opposite direction.

6. A fabric joint as in claim 5 wherein the second and third sections (44, 48; 76, 80) intersect the first section (40, 72) generally at a right angle.

7. A fabric joint as in claim 4 wherein the second and third sections (44, 48; 76, 80) each extend in the same direction from the first section (40, 72), and wherein the first section (40, 72) extends outwardly from the second section (44, 76) in one direction and outwardly from the third section (48, 80) in the opposite direction.

8. A fabric joint as in claim 1 wherein the second section extends outwardly in one direction from the intersection (168) which is between the side edges of the first section.

9. A fabric joint as in claim 8 which is formed with the sections generally in the shape of a Y.

10. A fabric joint as in claim 1 wherein said fiber bundles are made of graphite.

11. A fabric joint as in claim 1 wherein said fiber bundles are made of fiberglass.

12. A three dimensional woven connector comprising

a first generally planar section (40, 72) of flexible fabric composed of fibers which run lengthwise and are interwoven with fibers which run crosswise generally at right angles to the lengthwise fibers, and a second generally planar section (44, 76) of flexible fabric composed of lengthwise and crosswise fibers interwoven generally at right angles to one another, said second section (44, 76) of fabric being interwoven with said first section of fabric along an intersection (52, 146, 168) of the two sections, where at least one lengthwise fiber is common to the two sections, and

wherein at least some of the crosswise fibers of each section (40, 72) extend from said each section through the intersection to the other section.

13. A woven connector as in claim 12 wherein at least some of the crosswise fibers (184) are interwoven with the lengthwise fibers (180) to extend in one direction to the edge of a section and then about the edge and back in the opposite direction.

14. A woven connector as in claim 12 further comprising a third generally planar section (48, 80) of flexible fabric composed of lenghtwise fibers interwoven generally at right angles to one another, said third section (48, 80) of fabric being interwoven with said first section (40, 72) of fabric along a second intersection (56, 150) of the first and third sections, where the second intersection (56, 150) is generally parallel with the first mentioned intersection (52, 146) and where at least one lengthwise fiber (120, 130) is common to the first and third sections.

15. A woven connector as in claim 14 wherein the second and third sections (44, 48) each extend laterally in opposite directions from the first and second intersections (52, 56) respectively, and wherein the first section (40) extends outwardly from the second section (44) in one direction and outwardly from the third section (48) in the opposite direction.

16. A woven connector as in claim 14 wherein the second and third sections (76, 80) each extend in the same direction from the first section (72) generally in parallel to one another, and wherein the first section (72) includes lateral portions which extend outwardly in opposite directions from the second and third sections (76, 80).

17. A woven connector as in claim 13 further comprising a third generally planar section of flexible fabric composed of lenghtwise and crosswise fibers (164, 160) interwoven generally at right angles to one another, said third section of fabric being interwoven with said first and second sections of fabric along said intersection (168) where at least one fiber (160, 164) is common to the first, second and third sections.

18. A woven connector as in claim 17 wherein said first, second and third sections extend radially outwardly from said intersection (186), each at an angle with respect to the others.

19. A joint between a sandwich skin section (38) of an aircraft component and an elongate structural spar element (34) wherein the skin section comprises a core bounded on opposite faces by inner and outer face sheets, said joint comprising

a longitudinal groove extending from the underside of the skin section (38) into the core of said section, a strap-like woven fabric connector extending longitudinally along the groove and formed by a pair of second and third substantially parallel spaced web-like woven fabric sections (44, 48) intersected by a first web-like woven fabric section (40) to provide the connector with a substantially H-shaped cross-section in which the first selection (40) forms the crossbar of the H and has portions projecting transversely from opposite sides of the two spaced sections (44, 48), each of the sections comprising a plurality of multi-filament yarn strands extending side-by-side transversely to the longitudinal intersecting section or sections, the portions of the second and third spaced sections (44, 48) of the connector on one side of the first section (40) being received in the groove and adhesively bonded to the exposed edges of the core along the side walls of the groove,

and the transversely projecting portions of the first section (40) overlying and being adhesively bonded to the underside of the skin section (38) on opposite sides of the groove whereby the first section (40) bridges the groove and restores the continuity of the underside of the skin section (38),

a structural insert-section (60) filling the void in the groove between the portions of the second and third sections (44, 48) within the groove,

and the spar element (34) having a longitudinally extending edge received between the portions of the second and third spaced sections (44, 48) on the other side of the crossing first section (40) from the groove, said section portions overlying and being adhesively bonded to the opposite faces of the spar element (34) whereby the second and third spaced sections (44, 48) form continuous load paths between the spar element and the inner and outer face sheets of the skin section (38).

20. A joint according to claim 19, in which the transversely extending yarn strands of each section are formed by a continuous multi-filament strand which is woven back and forth across this section.